Rosie. There are I believe 2 separate questionnaires to be completed. The DR1 is a DVLA form that you need to complete and send back to them as an HRO. Depending on your replies, they will then decide whether or not to write to your GP, which given what you have said, in your case it will probably be no.
The DVLA Doctors questionnaire is I understand a different one and no one seems to be able to find a copy anywhere online (although I am sure it exists.)
I know what you mean about being a passenger. I hate that as well and always want to be in control of the car, so I don't think your nervousness is anything unusual. You obviously don't own a car and and intend hiring one. I'm not really sure of car hire companies policies towards DD offenders, but from what I can gather, it might be difficult for you to hire a car in this country for much longer than the 5 years quoted, if ever. If that's what you intend to do, then the best idea would be to call a few of them and ask what their policy toward DD offences is. Buying you own car, even a cheap one, might be the best way forward. Also if you are nervous about driving again after 4 years+, then a few refresher lessons with a driving instructor might be useful.
Another issue to consider is travel. You (and I,) now have a criminal record. Travel to the USA is generally ok. Canada stipulates that you need to wait 10 years after your conviction before applying for entry and Mexico will not allow you to enter, ever (as far as I know.) Most EU travel is okay, but I don't know about travel further afield.
There is then also the problem of getting insurance for any car you drive. I'm 61 so even without a no claims discount, I am hoping it won't be too excessive, but I'll need to pay what I'll need to pay.
The forum can be useful, but you need to be careful that you don't read too much into anyone's answers to your questions as unless you are a repeat offender, then most of us will only go through this process once and I'm sure you agree , once is enough.
I got over the guilt trip a while ago. It happened, it's done, it's in the past, don't make the same mistake again and get on with life. Everyone who knows about it amongst my family and friends have been generally supportive. Some of friends has been really good and are happy to drive us around on occasion when we need it. No one I've told has been excessively critical as they realise that what happened was completely out of character. I get the feeling that you are still beating yourself up about it but provided you have as we say in Scotland 'screwed the heid' then you should not feel guilty. Just remember all the people who may be judging you will also have things going on that I'm sure they don't want you to find out about.
Hopefully you didn't injure anyone or damage any property when you were caught and to be honest, sometimes being caught is the best wake up call you can get, especially for your overall health.